overallotment option

Dyne Therapeutics announced the pricing of an upsized underwritten public offering of 18,980,478 common shares at $18.44 per share, targeting $350 million in gross proceeds before fees. All shares are being sold by the company, with a 30‑day overallotment option for underwriters to purchase up to an additional 2,847,071 shares. The offering is expected to close on or about December 11, 2025, subject to customary conditions. Morgan Stanley, Jefferies, Stifel and Guggenheim Securities serve as joint book‑running managers.